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The "main reason" that we've attached so much importance to the BLS data is because it's so timely, according to economist Justin Wolfers. Meanwhile, "politics, campaigns, elected officials react to [the data] in real-time," adds Politico's Ben White — making it perfect fodder for today's overheated media cycle.

I spoke with both Wolfers and White in early June to test a theory: That there are three ways we get fooled by the jobs data.

1. Enormous margin of error

First, the numbers we get on those Friday mornings are exactly inexact. The BLS is transparent about it, at least. Their official margin of error for any given month is 100,000 jobs.

To be clear: One hundred thousand jobs! (As The Economist's Ryan Avent dryly observed, "there is a 90% chance that employment rose [in March] by between 20,000 and 220,000 jobs.")

In a healthy economy, where employers add several hundred thousand new positions each month, that margin of error matters less. But at current levels of hiring — with BLS reporting about 100,000 new jobs created per month — "you're taking about the margin of error of the entire thing," according to Politico's White.

Take that infamous September 2011 report. BLS reported that there were zero jobs created in August, throwing the market into a tailspin. But the agency later revised its estimate to 100,000 new jobs, before settling back at 85,000 jobs created in August.

All within the margin of error — and all perfectly unsettling for the market.

2. Persistent undercounting

As Wolfers and other economists know, initial jobs reports tend to get revised upward in a recovery or downward in a recession. That factors into their analysis and expectations.

But most observers don't realize just how much the jobs report has tended to undercount gains in the past two years, even during the nation's mild recovery. Because the initial number is a best guess, the agency needs a few months to fine-tune its data; BLS occasionally redoes its seasonal analysis, too.

Try adding up what BLS initially reported versus what we know now. Between June 2010 and June 2012, you'll find that the agency's first report under-counted job creation by more than 750,000 new jobs.

That's a reporting shortfall of 36,000 jobs per month – and maybe there's not much actual difference between hearing that the nation added 85,000 new jobs per month and 120,000 jobs, on any given Friday.

But White and others agree: There's a psychological risk when the media trumpets the initial number and scarcely revisits the revisions.

When the BLS reported that the nation gained zero jobs in August 2011, the story headlined the New York Times. But when the agency later upgraded those figures, the Times obliquely noted that BLS "also revised [previous] estimates upward" as part of the next month's story. There was no mention of the actual revision.